All Sky Camera/Weather Station build

[angryowl]

I always wanted to build my own weather station but I never seemed to have the time so it was always set aside as a future project. I have gathered some parts over the last couple of months and now it’s reached a point where I feel I must start designing and putting it all together.

The plan is to incorporate an all sky camera into it as I’ve always loved the idea of capturing satellites, meteors, aircraft, and iridium flares. Also having a constant view of the sky presents the advantage of not having to go outside to check for clear skies when starting an imaging session (some may say this is me being lazy but I find it rather convenient )

I will be logging progress on this thread as I go along as I feel it’s a good way of keeping track of where I am and what comes next.

Parts:

Opticstar DS-616C XL TEC colour CCD camera (same camera as the MallinCam Universe)

Meike 6.5mm f/2.0 180 degree circular fisheye lens

Cyclone Mini PC dongle

Heatsink and fan for the mini PC, separate adapters for the camera, mini PC and stepper drivers and dew heater

Arduino Mega 2560 R3 microcontroller, 1TB HDD, stripboard for electrical components, USB hub, cage fan for the enclosure, USB Ethernet adapter, some copper clips for holding the dew heater coil, jumper wires and some sensors

For the wind vane I will be using an MLX90316 rotary position sensor

The rain gauge and anemometer will be using two A3144 hall effect sensors. A Stevenson screen will house a BMP280 for temp and pressure, and an AM2301 for temp and humidity.

Most of the parts I plan on printing with either white PLA or ASA on my Wanhao duplicator I3 3d printer. Still have not decided on this yet as I am not sure on the extent of UV damage white PLA can take before breaking down. At the moment I have two options; print all in PLA and only flash with aluminium the main camera housing for increased UV protection, or print main housing in ASA which can withstand UV much better and the rest such as anemometer, rain gauge etc in ASA or PLA as when they degrade or break down a replacement can easily be printed.

I’ve finished some 3D models of various parts already and will be updating this thread soon.

 

[LightBucket]

Watching with interest

[Gina]

Me too

I have built an all sky camera and have a weather station project half built but shelved ATM.  Whether it gets finished depends on how I feel, what other projects take priority and how long I live

[angryowl]

Since the lens had a APS-C connector, this had to be sanded down to the point the lens would fit snugly into the opening of the camera as can be seen below.

At f2.0 figuring out precisely where the lens must be placed in relation to the camera was a real pain and unfortunately I have sanded way past that point and to get into focus the lens must now be lifted with a plastic washer as seen here.

Last night was clear and I managed to reduce the spacer by sanding and then testing until good focus was achieved in roughly the middle of the focus ring travel. The spacer will sit between the lens and camera and the three grub screws on the camera lip grab the lens quite well and keep in tightly in place.

More to come on this as I'm currently printing prototypes for holders for the focus and aperture stepper motors 

[angryowl]

12 minutes ago, Gina said:

Me too

I have built an all sky camera and have a weather station project half built but shelved ATM.  Whether it gets finished depends on how I feel, what other projects take priority and how long I live

I have to say Gina, that I have closely followed your all sky camera projects/versions and I have borrowed a great deal of ideas from there which I plan on incorporating here so thank you for taking the time to document it all, very useful stuff indeed.

[Gina]

Very glad you can make use of it - that's good to know  - thank you

[angryowl]

In addition to focus and aperture control I am working on a retractable lens cover which will be used when I need to take darks for the camera. What I'd want is with the help of the Arduino and an LDR to map LUX values to the resistance of the LDR, of course there won't be a linear correlation between the two values but we'll cross that bridge when we get to it. But the end result should be something along the lines of: if LDR goes over a predetermined value it's dusk so it should automatically move the cover to the ON position thus protecting the sensor from the Sun's rays during the day. Once the LDR falls bellow a certain value i.e. dusk the cover should be moved to the OFF position to allow for recording of the night sky. Well that's all theory at the moment

The lens cover will be painted with matte black paint on the inside so little to no light reflects into the lens during dark exposures.

This would be the lens cover in the OFF position

And the ON position...

Focusing mechanism holder for the stepper motor

And aperture holder for the stepper motor

Gears for the focus and aperture should fit tightly on the lens rings thus no gluing required there. Most of these parts are held together by M4 nuts and bolts and I think they should stick together nicely.

The whole assembly is mounted to the camera by 4 M3 screws on the side of the camera (not seen in the pictures above). 

[CharlP6]

Are you doing some form of FEA on these parts? The models seem meshed for that purpose. Or is it just the modeling software, perhaps for the printing?

[angryowl]

1 hour ago, CharlP6 said:

Are you doing some form of FEA on these parts? The models seem meshed for that purpose. Or is it just the modeling software, perhaps for the printing?

Had to look up the acronym (Finite Element Analysis) as I hadn't heard of it before 

I got into 3d printing only recently and the Wanhao is my first printer (and quite a good one too, when it works that is) and I have mainly used the Autodesk 123D Design software as I found it to be very user friendly for beginners as compared to others. It isn't great once you start getting into more advanced features and becomes cumbersome. One of it's most annoying quirks is the way it converts meshes to solids or when it refuses to do it at all. 

So I think that's what you're seeing in the models, some objects not being represented as solids but rather as meshes? But to answer your question, no I don't do FEA on the parts, it's just 123D Design being what it is.

[angryowl]

The main body enclosure holding most of the hardware needs to be as watertight as possible. 

Main box. 0.5mm thick walls and 12 6mm holes for attaching the acrylic dome and the lid

On the other side is where the M6 nuts will sit

On top of the box there's first a silicone gasket/seal

Followed by a 7mm thick printed lid, this will of course have cutouts for the camera lens and some other stuff which will protrude through 

After the lid comes another silicone gasket for the dome's 20mm lip

And finally the clear acrylic dome itself secured to the main box by 8 M6 bolts 

The acrylic dome I plan on using is this one http://www.ebay.co.uk/itm/CLEAR-PERSPEX-ACRYLIC-DOME-150mm-Diameter-with-20mm-wide-flange/272585583893?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2060353.m2749.l2649

The plan is to print molds for the two silicone seals, then use either regular acetoxy sealant silicone I have laying around and fill them, let them dry then peel them off. I'll have to test if this actually works and the silicone does not stick to the mold, I could try different types or brands until I find one that peels easily while retaining it's shape. the alternative would be to try two part silicone, but I will give the sealant a try first though.

Not sure what's a right thickness for the seals, but I figure 2mm should do it.

Any comments suggestions on the seals, is silicone the best way to go about it? Does this actually have a chance of working? I thought of flexible 3D filaments such as NinjaFlex or FilaFlex but not so sure on their waterproofing capabilities.

[CharlP6]

1 hour ago, angryowl said:

Had to look up the acronym (Finite Element Analysis) as I hadn't heard of it before 

I got into 3d printing only recently and the Wanhao is my first printer (and quite a good one too, when it works that is) and I have mainly used the Autodesk 123D Design software as I found it to be very user friendly for beginners as compared to others. It isn't great once you start getting into more advanced features and becomes cumbersome. One of it's most annoying quirks is the way it converts meshes to solids or when it refuses to do it at all. 

So I think that's what you're seeing in the models, some objects not being represented as solids but rather as meshes? But to answer your question, no I don't do FEA on the parts, it's just 123D Design being what it is.

Ah okay, that makes sense. It would have been interesting to see why you would have done FEA, not that it's necessary.. 

On the CAD topic, you may want to give Autodesk's Fusion 360 a go. It is a quite user friend parametric mechanical design package and its quite easy to get a grasp of. A big plus is, as a personal user, you get full functionality for free, and the whole package is a small download, less than 100MB if I'm right.

Anyway, I like your ideas for controlling the lens and would like to see it take form over time.

[CharlP6]

11 hours ago, angryowl said:

 

Any comments suggestions on the seals, is silicone the best way to go about it? Does this actually have a chance of working? I thought of flexible 3D filaments such as NinjaFlex or FilaFlex but not so sure on their waterproofing capabilities.

I'm not a sealant expert, but I get the idea that the silicone seals will crumble if you apply too much pressure, from my experience it is quite brittle.

Have you thought of getting a gasket kit and cutting it into the required shapes? Maybe you can print a gasket cutter for your required shapes?

Another suggestion is to use liquid gasket. I don't know if you can mould it and then use it after it cured (it would be interesting to see results of that) , but you can print/machine a recess in the parts you want sealed and then apply the gasket paste. If you tighten the lids, the gasket paste will flow into all the grooves and create a good seal once cured. If you want to service it, you just remove the old gasket and apply new paste when closing everything up

[angryowl]

2 hours ago, CharlP6 said:

I'm not a sealant expert, but I get the idea that the silicone seals will crumble if you apply too much pressure, from my experience it is quite brittle.

Have you thought of getting a gasket kit and cutting it into the required shapes? Maybe you can print a gasket cutter for your required shapes?

Another suggestion is to use liquid gasket. I don't know if you can mould it and then use it after it cured (it would be interesting to see results of that) , but you can print/machine a recess in the parts you want sealed and then apply the gasket paste. If you tighten the lids, the gasket paste will flow into all the grooves and create a good seal once cured. If you want to service it, you just remove the old gasket and apply new paste when closing everything up

Have considered getting rubber sheets and cutting them to shape but most of the ones I found were I think too hard and would probably not have worked? However I have not thought of gasket kits. A quick search only brings up pre-cut gaskets mostly for engine blocks, but I was able to find loads of gasket sheets which I could then cut.

Hmm, I like the idea of liquid gasket. Do you have any experience with it? Reason I ask is I wonder how difficult it would be to remove the lid or dome after it has cured. I suppose I could try moulding it, see if that works. Anyway will definitely give this a go if I've no success with either silicone or gasket sheets.

[SilverAstro]

Silicone RTV will peal easily from many things (except glass) for ex. I have used it as gasket on aluminium. No experience with printed plastic though ! So yes, a trial is indicated   you could google silicone mold making (for resin / plaster etc casting) where they use a release agent when preparing the dam to contain the setting mold.  I have seen varnish, vaseline or other grease and pva glue mentioned, but I have yet to try my first !

PS it is quite fragile when thin, so you may need to re-do it ( as I did with my aluminium castings) each time you part the assembly.

 

[SilverAstro]

Hmmm, more thoughts :-

that fragility problem was exaggerated in my aluminium experience because it was very thin indeed having been still liquid when presenting the two parts, also I was routinely replacing it anyway as it was cheap enough.

When peeling from glass as a bead it is not so bad. When disassembling a fish tank to repair it can be sliced off, from being stuck to the glass, but apart from that damage the resulting pieces were quite stable but very thick compared to what you are doing.

another thought  O-rings come in many different sizes ???

[angryowl]

41 minutes ago, SilverAstro said:

Silicone RTV will peal easily from many things (except glass) for ex. I have used it as gasket on aluminium. No experience with printed plastic though ! So yes, a trial is indicated   you could google silicone mold making (for resin / plaster etc casting) where they use a release agent when preparing the dam to contain the setting mold.  I have seen varnish, vaseline or other grease and pva glue mentioned, but I have yet to try my first !

PS it is quite fragile when thin, so you may need to re-do it ( as I did with my aluminium castings) each time you part the assembly.

 

I've seen how two part silicone moulding is done and before the silicone is poured, the inside of the mould is sprayed with what I believe is the release agent you are referring to and after curing it peels off easily. The mould for this was printed with PLA so that makes me think it would work for my gasket even if it's only 2mm thick.

Good to know about RTV as well as this adds another option if all the others fail.

I have no problem with re-casting a fresh one every time I open the box for servicing as I think whichever option I go for should be relatively inexpensive.

[Gina]

I've used 3D printed TPE filament gaskets quite successfully   I have a reel of TPU filament due to arrive anytime now and will see how that compares - it's reckoned to be easier to print.  We'll see

[angryowl]

I have a 10m TPU sample and found it very easy to print with. I used it to print winged eyecups for two of my diy widefield binos but found them to be a bit too hard for my taste so might re print in something softer. If I remember correctly I increased both bed and extruder temps by about 10 or 15 degrees and decreased the speed to around 10mm/s.

[angryowl]

I've finished printing the holder for the lens cover stepper motor and currently printing the rest of the holders for the steppers.

[angryowl]

The stick is now ready to go and has the heatsinks and fan attached to it. Used 1mm thick silicone thermal pad between the heatsinks and stick.

The whole assembly will be mounted inside the box via the 2mm holes seen on the corners of the motherboard.

The thin wire coming off of the side of the stick goes to the power button and will let me turn the stick on with the Arduino.

I've written and tested code so that about 30 seconds after the Arduino powers up it sends a DigitalWrite signal to an optoisolator hooked up to these wires turning the stick on. This will be done so when power is cut off from the mains to the weather station either accidentally or on purpose, and comes back up, the Arduino will be powered on first through the stick's USB port and run the code after 30 seconds turning the stick back on.

[angryowl]

Ahh, don't you just love a clogged nozzle and your printer resetting halfway during a 10hr print...

Anyway, couldn't resist and did a test last night and I'm impressed by the result considering my skies are Bortle 7.

30s exposure, no cooling, single frame dark subtraction.

_30.bmp

I never would have thought I'd be able to see the summer Milky Way through this from my light polluted skies, barely visible though but it's there all right. I'm loving the huge aperture and light collection of this lens 

Compared to a test I did a few months ago with my GPCAM and 1.25mm 180 degree lens, the difference is astounding!

[SilverAstro]

2 hours ago, angryowl said:

I never would have thought I'd be able to see the summer Milky Way through this from my light polluted skies, barely visible though but it's there all right.

He's right, it's there !

Very impressive

and ohhh! I think you have caught ( alerted us to) chy Cygnus at or near max ? mag3.3 to 14.2 +/-  It's been a long time since I looked at it, I forgot to ! and I was out looking at that region in the gaps last night.

 

[SilverAstro]

Have I blundered most horribly and miss-identified ? AAVSO LCG shows it as only about mag7.5 at the mo.

[SilverAstro]

Apart from AAVSO having it as Khi Cyg I cant see what is wrong

maybe a sudden jump ? Sadly the cloudGods are conspiring against me 

 

[angryowl]

Printer issues now resolved and printing the rest of the holders then gears.

Meanwhile I designed the Stevenson screen together with an arm and clamp which will be mounted on a 50mm diameter aluminium pipe, the same pipe on which the entire weather station will be on. The pipe is 1300 mm in length and I have another one in which the 50mm one fits like a glove, this is 800 mm long. Not sure at the moment if I will combine them as don’t know if I need the extra height.

Standard height for temperature and humidity is 1250 mm and for wind speed 10 meters 
http://www.weatherstations.co.uk/gooddata.htm

Also finished printing the aperture stepper holder

The Stevenson screen is split into two parts

One that clamps onto the pipe

And the other that slides into the first one and is secured with a 5 mm bolt. The other side connects to the bottom plate of the Stevenson screen with two 5 mm bolts.

The top plate has the mounting holes for the two sensors

The Stevenson screen is not my own design. It belongs to larosta from Thingiverse https://www.thingiverse.com/thing:1386333 So all credit goes to larosta. I just modified it to my needs.